Adjuvants have been used to facilitate vaccines in affording immunization to protect animals including humans. Identifying an efficient and effective adjuvant is often a difficult task.
Of particular interest are vaccines for protecting against influenza viruses, and of current interest avian influenza virus H5N1 (bird flu) including Vietnam and Hong Kong strains. Inactivated vaccines against influenza virus have been administered parenterally to induce serum antibodies and also to the nasal mucosa to provide mucosal immunity to influenza virus.
Several adjuvants are known such as alum, squalene emulsion (MF 59, Chiron Vaccines), and Freund's adjuvant. Recently a synthetic dsRNA polyriboinosinic polyribocytldylic acid or poly (I:C) has been proposed as an adjuvant or immuno-stimulant for inactivated influenza virus vaccine; see Ichinohe et al, Journal of Virology, March 2005, p. 2910-2919.